The present invention provides an improved golf putter that imparts a desireable over-spin to a putted ball even if the head of the putter is in a non-ideal orientation. An earlier putter designed to provide over-spin also tended to produce less than optimum results when held in an improper orientation.
In an earlier patent (U.S. Pat. No. 4,881,739) that addresses the same general subject matter, the inventor provided a detailed discussion of the extensive prior art of putter design and taught a putter with a cylindrical facing having a radius equal to that of a golf ball (0.84 inch), and made so that the face had its most forwardly projecting point elevated from the sole of the club by a height substantially equal to that radius. This design ensures that a putted ball is always contacted at or above its center of gravity. Contacting the ball above its center of gravity provides the ball with a desireable over-spin. The disclosure of U.S. Pat. No. 4,881,739 is incorporated herein by reference.
The putter design taught in U.S. Pat. No. 4,881,739 was based on an idealized geometry--i.e. one in which the axis of the putter head is parallel to the putting surface and the bottom of the putter is only slightly elevated above that surface. Extensive tests on the putter of U.S. Pat. No. 4,881,739 indicated that deviations from this ideal geometry led to poor results more quickly than did comparable deviations when putting with a conventional flat-faced putter. This particularly affected golfers who had trained themselves to putt with either the heel or toe of the putter slightly elevated.
Some known putter designs attempt to compensate for small deviations from ideality in the stroke geometry. Among these are designs that employ concave impact surfaces and that are forbidden by the Rules of Golf. The teaching of the present invention is entirely directed at golf putters that satisfy the Rules of Golf and that are therefore usable in tournament play. Hence, devices with concave impact surfaces are of no interest to the present case. Of interest is a putter with legitimate convex surfaces, as taught by Barr in U.S. Pat. No. 3,989,257. Barr provides an impact surface defined by intersecting horizontal and vertical ellipsoids, and claims that this surface is well suited to compensate for minute movements of a golfer's wrists during putting.
Other known designs, such as that taught by Witherspoon in U.S. Pat. No. 3,759,527, provide for golf clubs with convexly curved striking faces that accentuate the effects of how the club is held and used. These devices cause any imperfect swing to result in a missed shot, and claim utility only as training aids. Such devices are of no interest to the present case.